On March 23, architect, engineer, ecologist, educator and master of biomimicry Frei Otto was to be named as the 2015 recipient of architecture's top honor, the Pritzker Prize.

Otto, however, passed away at the age of 89 this past Monday in his native Germany, prompting Pritzker Prize officials to unveil this year's winner nearly two weeks earlier than planned. The second German architect to be bestowed with the prize in the 37-year history of the uber-prestigious award, Otto is the first Pritzker laureate to be honored posthumously.

He was to turn 90 this May.

The Berlin-reared, Stuttgart-based architect knew it was coming — that is, he was well-aware that his vastly influential career would be celebrated with a Pritzker Prize, largely considered to be Noble Prize of architecture. Shortly after the 2015 jury settled on its decision to name Otto as this year's laureate in January, the prize's executive director traveled to Germany to break the news to the architect in person at his long-time home and studio in Warmbroon, outside of Stuttgart.

A humbled Otto said this upon learning the news:

I am now so happy to receive this Pritzker Prize and I thank the jury and the Pritzker family very much. I have never done anything to gain this prize. My architectural drive was to design new types of buildings to help poor people especially following natural disasters and catastrophes. So what shall be better for me than to win this prize? I will use whatever time is left to me to keep doing what I have been doing, which is to help humanity. You have here a happy man.

While not a household name to most, Otto’s impact on modern architecture, particularly sustainable architecture, cannot be underestimated.

Best known for creating lightweight and ephemeral tensile membrane structures that stood as (literally) soaring testaments to the marriage of architecture and science, Otto, early in his career, was considered a neo-futurist (fellow polymath Buckminster Fuller was a friend and contemporary) and his tent-like creations were very much of the avant-garde. In divided 1960s Germany, where edifices were still being built to be bulky, rigid and non-transitory in nature, Otto’s creations resembled otherworldly big-tops zapped in from some strange and far-off cosmos. They were playful yet challenging, welcoming yet foreign, irregular-looking yet fastidiously engineered. Whereas most structures at the time remained firmly tethered to the ground, Otto’s work positively floated up toward the heavens.

An early work of Frei Otto: The Entrance Arch at the Federal Garden Exhibition in Cologne, Germany, 1957. (Photo: Atelier Frei Otto Warmbronn)

And whereas their futuristic curves seemed to have been imported from another galaxy, Otto’s work, largely defined by swooping roofs and organic forms, was vastly influenced by the natural world. Reads the Jury Citation:

Taking inspiration from nature and the processes found there, he sought ways to use the least amount of materials and energy to enclose spaces. He practiced and advanced ideas of sustainability, even before the word was coined. He was inspired by natural phenomena — from birds’ skulls to soap bubbles and spiders’ webs. He spoke of the need to understand the 'physical, biological and technical processes which give rise to objects.'

Today, Otto’s impact can be seen and experienced everywhere — in stadia like London’s Millennium Dome and the Georgia Dome in Atlanta; transportation hubs like Denver International and Grantley Adams Airport in Barbados; in the output of established starchitects such as Zaha Hadid and Richard Rogers (both past Pritzker laureates in 2004 and 2007, respectively) along with new-guard mavericks like Thomas Heatherwick and Bjarke Ingels. The latter two architects’ recently unveiled master plan for the new, canopy-heavy Google campus in Mountain View, California, boasts a distinctly and undeniably Otto-esque flair.

Otto founded the Institute for Lightweight Structures at the University of Stuttgart in 1964. (Photo: Atelier Frei Otto Warmbronn)

However, Otto’s design influence — and humanitarian ethos — is perhaps strongest felt in the work of 2014 Pritzker laureate, Shigeru Ban, with whom the elder architect collaborated for the Japan Pavilion at Expo 2000 in Hanover. While’s Ban’s work isn’t necessarily tent-like, both architects specialize(d) in sturdy yet transient structures that take advantage of low-cost materials, tread lightly on the planet and can be easily assembled, disassembled and relocated. Like Otto, Tokyo-based Ban is a minimalist and environmentalist who largely eschews razzle-dazzle big-money commissions for meaningful projects that have a positive impact on the planet and the people who call it home.

Says Ban: "Working with Frei Otto was always a lesson in creative thinking. He often used an unexpected approach to find the most appropriate structural solution. I am truly indebted to Frei Otto for sharing his deep understanding and inventions in the field of structures."

Lord Peter Palumbo, chair of the Pritzker jury, eloquently reflected on Otto life in a media release issued the day after his passing:

Time waits for no man. If anyone doubts this aphorism, the death yesterday of Frei Otto, a titan of modern architecture, a few weeks short of his 90th birthday, and a few short weeks before his receipt of the Pritzker Architecture Prize in Miami in May, represents a sad and striking example of this truism. His loss will be felt wherever the art of architecture is practiced the world over, for he was a universal citizen; whilst his influence will continue to gather momentum by those who are aware of it, and equally, by those who are not.

Frei stands for Freedom, as free and as liberating as a bird in flight, swooping and soaring in elegant and joyful arcs, unrestrained by the dogma of the past, and as compelling in its economy of line and in the improbability of its engineering as it is possible to imagine, giving the marriage of form and function the invisibility of the air we breathe, and the beauty we see in Nature.

Below, you’ll find six essential works designed by Frei Otto — a man who “embraced a definition of architect to include researcher, inventor, form-finder, engineer, builder, teacher, collaborator, environmentalist, humanist, and creator of memorable buildings and spaces" — including his glorious, career-defining roofs that still stand today at Munich's Olympiapark and his first big project outside of Germany, the West German Pavilion at the 1967 International and Universal Exposition in Montreal.

And although Otto worked primarily overseas, he traveled to the United States on a frequent basis. In the early 1950s, as a young architecture student, Otto visited work by Frank Lloyd Wright, Charles and Ray Eames, Richard Neutra and Mies van der Rohe. He also studied at the University of Virginia during this period and, decades later, was awarded the Thomas Jefferson Medal in Architecture. During the late 1950s and early 1960s Otto periodically returned to the U.S., this time as visiting professor at various universities including Yale, Harvard, and the Massachusetts Institute of Technology.

The Pritzker Prize award ceremony will be held on May 15 at the Frank Gehry-designed New World Center in Miami Beach.